lOP Conference Series: Materials Science and Engineering
P A P E R • OPEN A C C E S S
Related content
The Improvement of the Closed Bounded Volume (CBV) Evaluation Methods to Compute a Feasible Rough Machining Area Based on Faceted Models
To cite this article: Himawan Hadi Sutrisno e ( a ( 2 0 1 7 lOPConf. Ser.: Maler. Sci. Eng. 215 0 1 2 0 4 1
- SLirlsce i-econslRic[iOf> based on point r-loui3 fr^T^ lasef scannmg syslgm X Q Wang, B Li and Z 0 Jiang - 3D Point Smoothening Ustng Mnflitiad
Lucal ReU'ession tor Reverse Fnmnefifimi
Nur llham Aminijilah Abdulqawi and Mohd Salman Abu Mansor
- Evaiuabon Melhod tor Low-Tenpe'alure PerTpfmance of i itiii',jni Baltpr,' H W Wang, Q Ma, Y L Fu et al,
V i e w the article online for updates and enhancements.
l O P ebooks
TMal publishing witti leading voices STEM research.
coiiection - download the firsf every title for free.
T h i s c o n l e n l w a s d o w n l o a d e d from IP a d d r e s s 1 0 3 . 8 . 1 2 . 1 0 1 o n 1 5 / 0 4 / 2 0 1 9 a t 0 7 : 4 4
MOIME 2017 lOP Publishing lOPConf-Scries: MaierialsSciem-e and Engineering 215 (2017) 012041 dot: 10. IOR8/1757-8y9X/215/1/012041
The Improvement of the Closed Bounded Volume (CBV)
Evaluation Methods to Compute a Feasible Rough Machining Area Based on Faceted Models
Himawan Hadi Sulnsno'. Gandjar Kiswanio Jos Isliyanto '
' Mechanical Engineering Dept., Universitas Negeri Jakarta, Indonesia ' Dept. o f Mechanical Engineering, Universitas Indonesia, Depok, Indonesia
corresponding author: gandjar_kiswantoi@eng.ui.ac.id
Abstract. The rough machining is aimed at shaping a workpiece towards to its final form. This process takes up a big proponion of the machining time due to the removal of the bulk material which may affect the total machining time. In certain models, the rough machining has limitations especially on certain surfaces such as turbine blade and impeller. C B V evaluation is one of the concepts which is used lo detect of areas admissible in the process of machining.
While in the previous research, C B V area detection used a pair of normal vectors, in this research, the writer simplified the process to delect C B V area with a slicing line for each point cloud formed. The simulation resulted in three steps used for this method and they are; 1.
Triangulation from C A D design models, 2. Development of CC point from the point cloud. 3.
The slicing line method which is used to evaluate each point cloud position (under C B V and outer C B V ) . The result of this evaluation method can be used as a tool for orientation set-up on each C C point position of feasible areas in rough machining.
1. Introduction
Along with the development in the manufacturing industry, milling machine models have gone through a transformation with the purpose of fulfilling the consumers' needs. Although this transformation has significantly improved the complex models, the 5-axis milling still has its limitation. Also, there hasn't been any improvement of the machining method especially for rough machining. Until now, Ihe rough machining commonly adopts 3-axis machining methods. Certain models which contain the C B V need specific handling. This type of machining depends on machine operator's experience so it is likely for error to occur in the product.
At the same time, the developers are still trying to improve the model to solve other difficulties in the manufacturing. T o improve productivity, a new development melhod is needed for the machine to reduce the total machining time. This paper introduced a more advanced method called 5-axis milling for improving the rough machining efficiency.
2. Related work
In order to reduce errors during handling made by the operators, a few researchers have attempted to optimize the rough machining meihods[l-5], the tool orientation methods[6-8], the prevention of collision [9, 10], integrated C A M system[l 1], and the improvement o f tool sequence seleclion[12]
Con lent Irom this work may be used under the lertns of the Creative Commons Altri but inn 3,0 licence. Any further distribution I t this work must muiniain attribution lo the juthor|s) and the liile of Ihe work, journal citation and D O l .
Published under licence by l O P Publishing L i d ]
lOPCoiif. Series: Materials Science and Engineering 215 (2017)012041 doi: 10,1088/1757-899X7215/1/012041
There have been a few studies conducted discussing the C B V evaluations. Woo[13] introduced the concept of visibility cone which can be mapped onto a unit sphere. This visibility method provides an alternative way for detection i f there is an obstacle on the workpiece surface during the machining process. Siithunyatanakit, er al. [14]evaluated C B V by putting an obstacle on a light ray on the surface machining. I f the light ray is blocked by the obstacle, then the area w i l l be focused to calculate inaccessibility indication where it is not visible by the simple method.
Balasubramaniam ef. al. [10] proposed that graphic engine was used for visibility computation for generating collision free in 5-axis machining process especially for finishing. This concept uses a graphic hardware to show the machine limitation, the too! tilt and the accessibility tool for surface machining. L i , el al. [15] used the concept o f visibility to describe the reachability o f a light ray to the object surface.
In previous research, development C B V grouping method for complex faceted models has been presented by Kiswanto and Panuju[16] by pairing two triangles of normal vectors in one particular field and the two triangles were grouped in a bucket. The two triangles of normal vectors were grouped according to the machining characteristic surface which are C B V area and O B V area. The O B V area is usually called free surface without any obstacles for other surfaces. It needs a normal vector visualization which occupies the workpiece surfaces. In one workpiece model, the many triangles can be used to simplify the calculation process and for this purpose, bucketing method is required.
3. Improvement of C B V evaluation methods to compute feasible rough machining
In this study, the database for the calculation is the faceted models (triangulation), or also known the triangular mesh, polyhedral models, as well as tessellated models. This model has been used by many researchers due to its advantages in data processing and time computing. Since the C A D design is represented by a triangle, the shape of the triangulation result is an approximation. The accuracy o f triangulation depends on the number o f triangle resolution. Higher resolution results in a better shape visualization.
To get visualization needed, the computation uses Matlab software with S T L file as the first data.
The S T L file contains information related with the workpiece model, the features and the dimension of the workpiece which should be computed. The Figure 1 below is the C A D models while figure 2 illustrates S T L file formed. It can be seen in figure 2. the information needed in S T L file is the triangle positions in an indexed list as calculation objects.
2
MOIME 2017 lOP Publishing lOPConf, Series: Materials Science and Engineering 215 (2017)012041 doi: 10.1088/1757-899X/215/1/012041
s o l i d
f a c e t normal -I.OOOOOOOE-00 + 1 . 5 7 8 9 8 3 8 E - 1 6 + 1 . 7 3 6 8 8 2 2 E - 1 S outer loop
v e r t e x -S.OOOOOOOE+01 - 1 . 2 5 O O O 0 O E + 0 2 +0.OOOOOOOE+00 v e r t e x - 5.OOOOOOOE+01 - 1 . 2 S O O O O O E + 0 2 + 9 , O O O O O O O E + 0 1 v e r t e x - 5.OOOODOOE+01 - 3 , 5 0 0 0 0 0 0 E + 0 1 + 9 . O O O O O O O E + 0 1 endloop
endfacet
f a c e t normal -1.OOOOOOOE-00 + 1 . 7 3 6 8 8 2 2 E - 1 5 + 1 . 5 7 8 9 8 3 8 E - 1 6 outer loop
v e r t e x -5.OOOOOOOE+01 - 3 . 5 0 0 0 0 0 0 E + 0 1 + 9 . O O O O O O O E + 0 1 v e r t e x -5.OOOOOOOE+01 - 3 . 5 0 0 0 0 0 0 E + 0 1 +0.OOOOOOOE+00 v e r t e x -5.OOOOOOOe+01 - 1 , 2 5 O O O 0 O E + O 2 +0.OOOOOOOE+00 end!OOP
endfacet
f a c e t normal +0.OOOOOOOE+00 + 0 , 0 0 0 0 0 0 0 6 + 0 0 -1.OOOOOOOE-00 outer loop
v e r t e x + 1 . 4 0 0 0 0 0 0 E + 0 2 - l , 2 5 O O O O 0 E + 0 2 +0.OOOOOOOE+00 v e r t e x - 5.OOOOOOOE+01 -1.2SOOOOOE+02 +0.OOOOOOOE+00 v e r t e x - 5.OOOOOOOE+01 - 3 . 5 0 0 0 0 0 0 E + 0 1 + O . 0 O 0 O O 0 O E + 0 O end!OOP
endfacet
f a c e t normal +0.OOOOOOOE+00 +0.OOOOOOOE+00 -1.OOOOOOOE+00 outer loop
v e r t e x -5.OOOOOOOE+01 - 3.SOOOOOOE+OI + 0 . 0 0 O 0 0 0 0 E + 0 O v e r t e x + 1 . 4 0 0 0 0 0 0 E + 0 2 - 3 . 5 0 0 0 0 0 0 E + 0 1 + 0 . 0 0 0 0 0 0 0 E + 0 0 v e r t e x + 1 , 4 0 0 0 0 0 0 E + 0 2 - 1 . 2 S O O O O O E + 0 2 +0.OOOOOOOE+00 end!OOP
endfacet
f a c e t normal +0.OOOOOOOE+00 -1.COOOOOOE+00 +0.OOOOOOOE+00 outer loop
v e r t e x -5.OOOOOOOE+Ol - 1 . 2 5 0 0 0 0 0 6 + 0 2 + 9 . O O O O O O O E + 0 1 v e r t e x + 3 . 8 7 5 9 8 2 6 6 + 0 0 - 1 . 2 5 0 0 0 0 0 E + 0 2 + 6 . 6 5 4 5 6 7 7 E + 0 1 v e r t e x + 4 . 9 2 8 8 2 7 6 E + 0 0 - 1 . 2 5 0 O 0 O O E + O 2 + 6 . 8 9 4 0 8 6 3 E + 0 1 endloop
endfacet
f a c e t normal + 0 . 0 0 O 0 0 O 0 E + 0 0 -l.OOOOOOOE+OO +0.OOOOOOOE+00 outer loop
v e r t e x + 5 . 6 1 3 2 1 9 5 E + 0 1 - 1 . 2 5 0 0 0 0 0 6 + 0 2 + 2 . 5 4 0 6 2 9 0 E + 0 1 v e r t e x + 5 . 3 2 5 8 5 2 0 E + 0 1 - 1 . 2 5 0 0 0 0 0 6 + 0 2 + 2 . 5 7 4 3 9 0 0 6 + 0 1 v e r t e x + 5 . 0 5 9 2 5 0 2 6 + 0 1 - 1 . 2 5 0 0 0 0 0 6 + 0 2 + 2 . 5 6 7 8 4 8 4 E + 0 1 endloop
endfacet
Figure 2. S T L file form
Referring to the explanations above, the principles of this method are :
3.1. STL reader and positioning lo coordinate system The S T L files ( A S C I I formal) contains the following data:
s o l i d
F a c e t n o r m a l O u t e r l o o p
V e r t e x Verte.x V e r t e x E n s l o o p E n d f a c e t
End
The content o f S T L file above are elaborated below:
1. Solid, E n d Solid, marks faceted models representation
2. Facet normal, provides information on the position of normal vector on a triangle 3. Outer loop, end loop are the looping of the coordinates of the vertices
4. Vertex is the point position of the triangle on the coordinate system,
The following is the data processing model used lo manage the S T L file which contains the data facet and vertices that form the triangle. The function of S T L reader can be seen in psedocode below:
3
lOPConf. Series: Maierials Science and Engineering 215 (2017) 012041 doi: 10.1088/1757-899X/215/1/012041
f o l d e r • ' f o l d e r name';
f i l e n a m e = ' f i l e name';
s t l p a t h = s t r c a t ( f o l d e r , '/', f i l e n a m e , ' . t x t ' ) ;
t r i a n g l e s _ c s v = s t r c a t ( f o l d e r , '/', f i l e n a m e , ' _ t , c s v ' ) ; v e r C i c e s _ c s v = s t r c a t ( f o l d e r , '/', f i l e n a m e , ' _ v . c s v ' ) ; i f e x i s t ( t r i a n g l e s _ c s v ) &S e x i s t ( v e r t i c e s ^ c s v )
d i s p ( [ ' R e a d f r o m f i l e . . . ' , t r i a n g l e 5 _ c E v , ' and ', v e r t i c e s _ c s v , ' . ' 1 ) ; T = c s v r e a d ( t r i a n g l e s _ c s v i ;
V = c s v r e a d [ v e r t i c e s _ c 5 v ) ; e l s e
[ T , V] = s t l r e a d e r ( s t l p a t h ) ; c s v w r i t e ( t r i a n g l e s _ c s v , T ) ; c s v w r i t e ( v e r t i c e s _ c s v , V ) ; end
The Matlab software is used to compute the above function to get information and position o f all triangles at coordinated positions. In addition lo the S T L read import function, here are two S T L reads with m flics available on the Matlab file exchange.
3.2 Generating of poinl clouds
B y triangulating the workpiece. the length, width and height of Ihe workpiece are calculated from triangle position against a three-dimensional plane. Location of the furthest triangle on X axis identifies the maximum value of x and the same thing shall apply to Y axis and Z axis. The workpiece dimension w i l l be counted from X mux to X min, for Y axis, from Y max to Y min, for Z axis, Z max to Z min
In the point cloud creation process, which was explained in figure 3, the distances between point cloud towards the flat plane as well as vertical plane are determined by the density value. Initial formation o f point cloud is carried out along a flat plane for example X Y plane from the minimum value to the maximum value. The point cloud here is a virtual point construction to simplify calculation and it is used as initial reference at the work piece surface. A s explained before, every point cloud on X Y place at elevation z = 0 is also made on each altitude level ( Z level) with the value between levels o f density equal to density o f point cloud. The making o f point cloud on every Z level is a layering step on the feeding process, considering the depth o f cut on the machining process.
F i g u r e 3. generated point cloud
3.3 Slicing line method
A
MOIME 2017
l O P Piiblishifi';
lOPCunf. Series: Materials SciciKe and Engineering 215(2017) 012041 doi:IO,1088/1757-899X/2I5/l/0!2041
B y using ray triangle intersection method, by Moller & T m m b o r e [ i 7 ] , this process produces less memories in computation. This step is needed to compute the intersection of ray with a triangle and e l V c ' h r ? 8 7 T ' \ ^ r '^^'^uT'^ 'h^^ intersection. Slicing melhod been applied in research] 1 s j . Look at figure 4 below:
F i g u r e 4. slicing line with ray triangle intersection method[17]
A ray with origin o and direction d intersects a triangle defined by its vertices, v^, v,, and v; and the ray intersects with a point at triangle areas by the equation of plane:
d = ax + by + cz
When a, b. c are coefficient forms, a vector o f the plane is [ab cf so the equations are n.x = d
And
X = [xy z]T
T o calculate the intersection o f the ray and the triangle, the equation above becomes:
/ ( t ) = o + t . d and
n . / ( t ) = d n .[tj + t . d ] = d
0 ) (2)
(3)
(4)
t = d-n. o
n .d
( 5 ) ( 6 ) ( 7 )
The function and simulation result (figure 5) are shown below:
f u n c t i o n [ f l a g , u , v , z] - r a y T r i a n g l e l n t e r s e c t i o n ( o , d, pO, p i , p2) I n p u t :
o ; o r i g i n , d : d i r e c t i o n .
pO, p i , p 2 : v e r t i c e s o f t h e t r i a n g l e . O u t p u t :
f l a g : ( 0 ) R e j e c t , ( 1 ) I n t e r s e c t . u , v : b a r y c e n t r i c c o o r d i n a t e s , t : d i s t a n c e from t h e r a y o r i g i n , e p s i l o n = 0 . 0 0 0 0 1 ;
e l = p l - p O ; e2 = p 2 - p 0 ;
q = c r o s s ( d , e 2 ) ;
a = d o t ( e l , q ) ; % d e t e r m i n a n t o f t h e m a t r i x M i f ( a > - e p s i l o n s s a < e p s i l o n }
( f l a g , u , V , t l = d e a l ( 0 , 0 , 0 , O ) ; r e t u r n ;
e n d ;
5
lOP Conf. Series: Materials Science and Engineering 215 (2017) 012O4I doi: 10.1088/1757-8y9X/215/1/012041
3.4 Slicing line thai culling thru a triangle
This subchapter will explain how to get the intersection o f the slicing line with a model (triangles). A s described in the previous subchapter, the virtual point cloud was computed by utilizing of a ray triangle intersection method. The distance of point cloud was formed by the density value. This means the position o f the point cloud as the object computation has been determined as the origin o f the ray.
The ray direction was determined by the direction o f Z axis as well as by adding the value oL{k) in the (i, y, k) vectors. Pointed on the equation above, each slicing line w i l l calculate o f (f) value where the value of {t) indicates intersection with triangle. Next, each slicing line wilt look like a triangle intersection by iterations and w i l l be stored in the data index. The steps to get the triangle to intersect with the slicing line as following:
c u t t i n g _ s l :
%% T h i s r e t u r n s f u n c t i o n sub_po
m i n s maxs d e n s i t y m i n _ x
f rom_x s l _ x _ f r o m t o _ x s l _ x _ t o m i n _ y from_Y t o _ y s l _ y _ f r o m s l _ y _ t o Eub_poiru:s end
f i n d a l l S L t h a t c u t t i n g t h r u a t r i a n g l e , sub e l e m e n t s o f p o i n t s c l o u d ' s u b _ p o i n t s ' . i n t s = c u t t i n g _ s l ( t r i _ v e r t i c e s , p o i n t s _ c l o u d )
= m i n ( t r i _ v e r t i c e s ) ;
= m a x ( t r i _ v e r t i c e s ) ;
= p o i n t s _ c l o u d ( 1 , 2 , 1 ) - p c i n t s ^ c l o u d ( 1 , 1 , 1 ) ;
= p o i n t s _ c l o u d ( 1 , 1 , 1 ) ;
= m i n s ( 1 ) ;
= c e i l ( ( f r o m _ x + d e n s i t y - m l n _ x ) / d e n s i t y - m a x s ( 1 ) ;
= f l o o r ( ( t o _ x + d e n s i t y - m i n _ x ) / d e n s i t y )
= p o i n t s _ c l o u d ( l , 1 , 2 ) ; - m i n s ( 2 ) ;
= m a x s ( 2 ) ;
= c e i l ( ( f r o m _ y + d e n s i t y - m i n _ y ) / d e n s i t y
= f l o o r ! ( t o _ y + d e n s i t y - m i n _ y ) / d e n s i t y ) - points_cloud ( sl_Y_£roni: s l _ y to, s i x_froin;sl_x to, ;
3.5 CBVdetenuinatiun
According with the previous description, for each triangle intersected by the slicing line will be stored at the database and will be evaluated for C B V area grouping. The grouping method is illustrated in figure 6 below. The basic concept is to classify the location o f each point cloud based on position at the models. The point cloud which is on C B V area is located between two solid models o f a slicing line whereas the point cloud as O B V area is located outside of C B V area and beyond solid models.
The point cloud at C B V area can be seen in figure 7 below.
6
lOP Publishing MOIME 2(1!7
lOPCotif. Series: Mjlerials Science and Engineering 21S (2017) 012041 doi: 10,1088/1757-899X/215/1/012041
Figure 6, the number of triangle intersection
Poinl cloud under CBV area
- Y t u t -
Figure 7. Result of C B V grouping
4. Result And Discussions
In Ihis study, the C C points under Ihc C B V area were determined by using virtual points in the form of point clouds. The distances among the point clouds were used as the base value, or what is known as the density value. Each point cloud became the reference to determine the grouping: C B V or O B V area. Meanwhile, in the previous study, the C B V and O B V are was determined before the point clouds were made and therefore, there were steps previously done lo determine the machining area which was simplified in this study.
Table 1. the difference between the previous and the new study.
Steps tor deierminaiion Previous New method method 1 S T L reader yes yes 2 Plot normal vector yes no 3 Calculate of average point yes no 4 Bucketing method yes no
7
lOP Publishing lOPConf. Scries: Materials Seicnte and Engmeering215 (2017)012041 doi: 10.1088/I757-899X/215/1/012041
5 Generating of point cloud yes yes 6 Paired normal vector evaluation yes no 7 Map matrix yes no 8 C B V grouping yes yes 9 Double C B V detection yes no
5. Conclusion
Compared to the previous concept, this method is simpler and more suitable for rough machining because the points used as computation objects are virtual points with certain distances so that the result data is still rough. The previous method is more suitable for finishing process because main point o f object computation uses triangles at surface curves.
References
f 1] B . L . G . K . J - P. Kruth, "Development of a Five axis Milling Tool Path Generation Algorithm based on faceted model," 2003,
[2] S. C . Park and Y . C . Chung, "Tool-path generation from measured data," Computer-Aided Design, vol. 35. p. 9, 2003.
[3] H , - T . Young. L . - C . Chtiang, K . Gerschwillcr. and S. Kamps, " A five axis Rough Machining Approach for a Centrifugal Impeller," The International Journal of Advanced Manufacturing Technology, p. 16. 2003.
[4] H . T . Young, L , C . Chuang, K . Gerschwiler, and S, Kamps, " A five-axis rough machining approach for a centrifugal impeller," The International Journal of Advanced Manufacturing Technology, vol. 23, pp. 233-239, 2004.
[5] M , Balasubramaniam, P. Laxmiprasad, S. Sarma, and Z. Shaikh, "Generating 5-axis N C roughing path directly from a tesselated representation," Computer-Aided Design, vol. 32, p.
17, 2000.
[6j Y . - S . Lee, ".Admissible tool orientation control o f gouging avoidance for 5 axis complex surfce machining," computer aided design, vol. 29, 1997,
[7] K . C . Cha-Soo Jun, Yuan-Shin Lee. "Optimizing tool orientation for 5-axis machining by configuration space search method," computer aided design, vol. 35, p. 18, 2003.
[8] G . Kiswanto, H . H . Sutrisno. and J , Isliyanto, "Development of Initial Tool Orientation
Method At Close Bounded Area for 5-Axis Roughing Based On Faceted Models," ICMM, vol.
3,2016.
[9] G . Kiswanto, B . Lauwers. and J.-P. Kruth, "Gouging elimination through tool lifting in tool path generation for five-axis milling based on faceted models," Int. J Adv Manuf Technol, vol.
32. p. 21.2007.
[10] M . Balasubramaniam, S. E . Sarma, and K . Marciniak, "Collision-free fininshmg toolpath from visibility data," Computer-Aided Design, vol. 35, p. 16, 2003.
[ I I ] J . P. K . B . Lauwers, P. Dejonghe. R. Vreys, "Efficient N C programming o f Multi axis Milling Machine Through the intregation o f tool path Generation and N C simulation," computer aided design, 2000.
[12] A . Krimpenis and G . - C . Vosniakos, "Optimisation o f Multiple tool C N C Rough Machining o f a Hemisphere as a Genetic Algorithm Paradigm Application," Int. J Adv Manuf Techno!, vol.
20. p, 8. 2002.
[13] W. T C , "Visibility maps and spherical algorithms," Computer Aided Design, vol. 26. p. 10, 1994.
S
MOIME 2(117 lOPPubiishmg lOPConf. Series: MaierinlsSeienee and Engineering215 (2017)012041 doi:10.1088/1757-89yX/2l5/l/0]2041
[14] K., Siithunyatanakit, E . L . J . Bohez, and K . Annanon, " A new global accessibility algorithm for a polyhedral model with convex polygonal facets," Computer-Aided Design, vol. 4 1 , p. 14, 2009.
[15] Y . L i and M . C . Frank, "Computing non-vi.sibility o f convex polygonal facets on the surface of a polyhedral C A D model," Computer-Aided Design, vol. 39. pp. 132-1AA, 2007.
[16] G . Kiswanto. and A . Y . T . Panuju, "Development o f closed bounded v o l u m e ( C B V ) grouping melhod of compiek faceted model through C B V Boundaries identification.," IEEE, vol. 3, p.
5, .September 2010.
[17] T . Moller and B . Trumbore. "Fast MinimumStorage RayTriangle Intersection," 1997.
[18] S. C . Park, "Sculptured surface machining using triangular mesh slicing," Computer-Aided Design, vol. 36, 2004.
9
